Digitoxin (Crystodigin)

Category:

• Cardiac

Description:

• Antidysrhythmic; cardiac glycoside

Indications:

• Congestive heart failure, atrial fibrillation, atrial flutter

• Paroxysmal atrial tachycardia (PAT)

• Cardiogenic shock

Contraindications:

• Ventricular tachycardia

• Ventricular fibrillation

Precautions:

• Pregnancy category C; passes readily into fetus; excretion into breast milk unknown

• Hypokalemia, hypomagnesemia, hypercalcemia, hypothyroidism, sick sinus syndrome

• Severe pulmonary disease, hepatic disease, AV block, acute MI, hepatic disease

• Wolff-Parkinson-White syndrome

Adverse Reactions (Side Effects):

• CNS: anorexia, apathy, confusion, delirium, disorientation, drowsiness, EEG abnormalities, hallucinations, headache, mental depression, neuralgia, psychosis, restlessness, seizures, weakness

• CV: atrial fibrillation, AV block, bradycardia, premature ventricular contractions (PVC’s), ventricular fibrillation, ventricular tachycardia

• EENT: visual disturbances (blurred, yellow or green halo effect)

• GI: abdominal discomfort, diarrhea, hemorrhagic necrosis of the intestines, nausea, vomiting

• HEME: eosinophilia, thrombocytopenia

• SKIN: rash

Dosage:

Administered orally (tablet)

• Adult:            Loading dose PO (rapid) 0.6mg, followed by 0.4mg, then 0.2mg at every 4-6 hour intervals; (slow) 0.2mg 2 times daily for 4 days; maintenance dose PO 0.05-0.3mg daily.  Dosage reduction not needed in renal function impairment

• Child:             Loading dose PO <1 year 0.045 mg/kg, 1-2 years 0.04 mg/kg, >2 years 0.03 mg/kg divided into 3, 4, or more portions with >6 hours between doses; maintenance dose PO 1/10 loading dose

Drug interactions:

• Alprazolam, amiodarone, diltiazem, verapamil, bepridil, nitrendipine, quinidine, carvedilol, cyclosporine, erythromycin and tetracycline (change in bacterial flora causing effect may persist for months), hydroxychloroquine, NSAIDS, azole antifungals, omeprazole, lansoprazole, propafenone, quinine, spironolactone, tacrolimus:  May cause increased digoxin levels

• Charcoal: reduced digitalis levels

• Beta-Blockers: Potentiation of bradycardia

• Succinylcholine: increased arrhythmias

Special considerations:

• Listed adverse effects are mostly signs of toxicity

• When digitalis indicated digoxin is 1st line drug because of shorter ½-life and faster clearance in the event toxicity develops.

• Rule out digitalis toxicity if nausea, vomiting, or arrhythmias develop

• Therapeutic range: 9-25 ng/ml